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// This method gives you an easier way of calling super
// when you're using Backbone in plain javascript.
// It lets you avoid writing the constructor's name multiple
// times. You still have to specify the name of the method.
//
// So instead of having to write:
//
//   User = Backbone.Model.extend({
//     save: function(attrs) {
//       this.beforeSave(attrs);
//       return User.__super__.save.apply(this, arguments);
//     }
//   });
//
// You get to write:
//
//   User = Backbone.Model.extend({
//     save: function(attrs) {
//       this.beforeSave(attrs);
//       return this._super("save", arguments);
//     }
//   });
//

;(function(Backbone) {

  // The super method takes two parameters: a method name
  // and an array of arguments to pass to the overridden method.
  // This is to optimize for the common case of passing 'arguments'.
  function _super(methodName, args) {

    // Keep track of how far up the prototype chain we have traversed,
    // in order to handle nested calls to _super.
    this._superCallObjects || (this._superCallObjects = {});
    var currentObject = this._superCallObjects[methodName] || this,
        parentObject  = findSuper(methodName, currentObject);
    this._superCallObjects[methodName] = parentObject;

    var result = parentObject[methodName].apply(this, args || []);
    delete this._superCallObjects[methodName];
    return result;
  }

  // Find the next object up the prototype chain that has a
  // different implementation of the method.
  function findSuper(methodName, childObject) {
    var object = childObject;
    while (object[methodName] === childObject[methodName]) {
      object = object.constructor.__super__;
    }
    return object;
  }

  _.each(["Model", "Collection", "View", "Router"], function(klass) {
    Backbone[klass].prototype._super = _super;
  });

})(Backbone);